Steering Wheel Capacitance Sensing for Reliable Hand-Off Detection
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Solution Overview
Problem
Conventional detection methods for automotive interior component occupancy, such as steering wheel and seats, suffer from reduced reliability due to mechanical switch wear and inadequate accuracy and response speed of pressure sensors, leading to misjudgment and delayed responses in complex scenarios.
Innovation Solution
A method involving a capacitance detection system with a metal wire and a conductivity-enhanced capacitance receiving layer that increases sensing area, allowing for improved sensitivity and accuracy by heating the interior component, sampling capacitance, and comparing it to a threshold, with a time-division multiplexing process to enhance detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitance receiving layer is added to increase sensing area, then sensitivity and detection accuracy are improved, but device complexity increases
Solution Approach 1:
The sensor is divided into multiple functional layers: a base substrate layer, a capacitance receiving layer with enhanced conductivity, and a metal wire sensing element. This segmentation allows each layer to perform its specific function optimally while collectively improving detection accuracy without excessive complexity.
Solution Approach 2:
The capacitance receiving layer uses composite material structure combining conductive materials with the substrate material. This composite approach enhances the sensing capacitance by creating multiple interfaces and charge pathways, thereby improving sensitivity while maintaining a manageable structural complexity.
2Measurement precision
If heating is applied to the interior component, then capacitance detection sensitivity is enhanced, but energy consumption increases
Solution Approach 1:
The heating is applied periodically rather than continuously, with heating pulses synchronized to the sampling periods. This periodic heating enhances capacitance detection sensitivity during critical measurement windows while minimizing overall energy consumption by allowing the system to remain in a lower power state between measurements.
Solution Approach 2:
Heating is applied in advance before capacitance sampling to pre-condition the interior component and enhance the capacitance signal. This preliminary heating action ensures optimal detection conditions are established before the actual measurement, improving sensitivity without requiring continuous energy input.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enhances sensitivity and accuracy of occupancy detection by increasing sensing capacitance, reducing misjudgment, and ensuring rapid response through the use of a conductivity-enhanced capacitance receiving layer, improving user experience and intelligent functions in automobiles.
Implementation Method 1
heating the automotive interior component through a metal wire in the heating period
Implementation Method 2
an occupancy situation is determined by a capacitance formed between the sensor metal wire built in the automotive interior component and a human body
Data Source
AI summary
Embodiments of the present disclosure provide a method for detecting a capacitance between an automotive interior component and a human body, including heating the automotive interior component through a metal wire in a heating period, acquiring a total human body occupancy capacitance through a metal wire in a sampling period, comparing magnitudes of the total human body occupancy capacitance and a capacitance threshold to obtain an occupancy situation of the automotive interior component, and repeatedly executing the above process.